1. Field of the Invention
The present invention relates to a high efficiency reflectometry illuminator collector system.
2. Discussion of the Background
Spectrophotometers may be used to measure the color spectrum on the surface of objects, such as paper, paint chips or fabric swatches. A spectrophotometer for reflectance spectrometry usually includes a light source, such as a light bulb and a power source, optics for transferring the light from the light source to the sample, such as fiber optics, lenses and/or mirrors, and optics for collecting the light, which may also include fiber optics, lenses and/or mirrors. The collected light is then transferred to a device for separating the light into its component wavelengths, such as a diffraction grading or a prism, and then to a detector to measure the intensity of one or more of the different wavelengths of the light. As a reference the intensity of one or more of the different wavelengths of the light. As a reference, the intensity of light generated by the light source may also be transferred by optics to a detector. The signal generated by the detector from the sample light, and the signal generated by the detector from the reference light, may be transferred through a data processing system, such as a computer, and the result displayed or stored. A large variety of configurations and methods are known, and are described in U.S. Pat. Nos. 5,701,175; 5,400,138; 5,319,437; 4,773,761; 3,885,878; and 3,806,256; all of which are incorporated by reference.
A typical geometry of optics closest to a sample in the directive (as opposed to integrating sphere) reflectometry industry includes illumination and collection sections, each with a specific angle from the normal to the sample surface, for example illumination at 45.degree. to the normal of the plane of the sample surface, and collection normal to the surface of the sample. With the exception of highly mirrored samples, all reflectance samples scatter light from the illuminator at various solid angles into the space above the sample. Only a portion of the scattered light is therefore collected by the collection optics, due to the collection angle. It would be desirable, therefore, to use this wasted scattered light, in order to boost the strength of the signal and improve the accuracy and precision of the spectrophotometer.